This invention relates to methods and devices for carrying out pleural or thoracic drainage of a patient. Such drainage is used to remove gas or air from the pleural cavity surrounding the lungs and also to remove blood or other liquids therefrom. Typically, such drainage is needed after chest surgery or the infliction of a chest wound, a lung puncture, or even from certain diseases.
In any event, such drainage is characterized by the application of very low vacuum since high vacuum could overextend the lungs or cause damage. The pleural drainage device maintains a very slight negative pressure in the pleural cavity, thus assisting in the expansion of the lungs by the patient to thus ease the effort or burden of patient breathing. The low negative pressures used, or present in the pleural cavity may range in the order of 5-20 cm water.
One well known system used to carry out pleural drainage is called the three bottle system, wherein one of the bottles is utilized for the collection of fluids from the patient, a second bottle is used to provide an underwater seal preventing backflow to the patient and still a third bottle used to regulate the maximum amount of vacuum that can be applied to the pleural cavity.
Various devices are currently on the market that combine the function of two or even three bottles of the aforementioned system.
The purpose of the collection bottle is, of course, obvious since it is merely a container or chamber for receiving the fluids that are removed from the patient via use of vacuum. The underwater seal bottle has the function of a check valve and prevents backflow to the pleural cavity or buildup of pressure in such cavity. Although the specific features of an underwater seal will be later explained, it is suffice to say that such seals are preferable in connection with pleural drainage inasmuch as they are functionable at extremely slight vacuum levels and flows used with pleural drainage and have no moving parts that could malfunction through sticking or other physical disabilities. As will be seen, a dangerous situation could occur in the event the check valve function in a pleural drainage system were to stick in the closed position.
In present devices combining a collection chamber and an underwater seal, the liquid, normally sterile saline solution, that is used to effect the seal itself, is added to the device just before the pleural drainage unit is utilized. Thus, the unit itself is manufactured and sold without the liquid, and when it is desired to be put into use, a volume of sterile liquid must be carefully measured and introduced, normally by pouring the same, into the pleural drainage unit to create the water seal. Difficulties occur in the possibility of spillage, thus making the desired volume inaccurate, the accuracy or inaccuracy of the volume measurement itself, and the ready availability of a sterile liquid at the location where the unit is to be utilized.
Other features of presently marketed pleural drainage units include the need to provide a water seal having a small volume such as to reduce dead air space yet, at the same time, the collection chamber should be of sufficient size as to receive fluids for a considerable period of time before becoming filled.
In addition, a desirable feature in pleural drainage units is the visibility of the water seal so that personnel attending to the patient can visually perceive bubbles in the unit evidencing good pressure within the pleural cavity during exhalation and thus provide an indication of the strength of the patient's breathing.
Accordingly, the present invention is concerned with overcoming certain problems presently existing in methods and apparatus to carry out pleural drainage, particularly with respect to the introduction of a liquid into the unit to form an underwater seal. The unit can be tipped over without losing the integrity and function of the underwater seal upon rerighting thereof. The underwater seal function of the unit is visible and does not introduce significant dead air space into the overall unit.